Wear rod

ABSTRACT

Improved wear rods for snowmobile skis are provided by bonding to the underside of a steel rod an elongated polyurethane member having alumina ceramic pellets embedded therein.

United States Patent Ambrose Nov. 20, 1973 WEAR ROD 3,707,297 12/1972 Perrault 280/28 [75] Inventor: Donald B. An br se Wi n gKa LlI.

' 7 Primary Examiner-Kenneth H. Betts [73] Assignee. martin L. Hausman, River Forest, Assistant Examiner Roben R. g

AttorneyGeorge H. Gerstman 22 Filed: Apr. 3, 1972 [21] Appl. No.: 240,580

[57] ABSTRACT [52] U.S. Cl 280/28, 161/168, 264/261 Improved wear rods for snowmobile skis are provided [51] int. Cl B62b 17/04 by bonding to the underside of a steel rod an elon- [58] Field of Search 280/28 gated polyurethane member having alumina ceramic pellets embedded therein. [56] References Cited 7 Claims, 3 Drawing Figures WEAR ROD BACKGROUND OF THE INVENTION This invention concerns improved wear rods for snowmobile skis and a method of producing the same.

Snowmobile skis conventionally have recesses therein to accept wear rods, or -skags, as they are sometimes called. Such wear rods are typically formed of steel, are elongated and bent substantially to the shape of the skis and carry bolts or the like for permitting their attachment to the skis. When the wear rod is attached to the ski, a portion of the wear rod is located below the bottom of the ski in order to prevent abrasion of the skis bottom. An example of a prior art wear rod is disclosed in the United States patent to Anthony Fox, No. 3,545,560, issued Dec. 8, 1970.

Persons who use snowmobiles frequently recognize the necessity to replace wear rods and the bottom of the skis must constantly be checked to determine if the wear rods need replacement. Frequent wear rod replacement is time consuming and expensive.

It is an object of the present invention to provide an improved wear rod that has a much higher abrasion re sistance than conventional steel wear rods.

It is a further object of the present invention to pro vide an improved wear rod which has a greater elasticity than that of steel, provides improved stability and increases the steering response of the snowmobile.

A still further object of the present invention is to provide a wear rod which has a lower coefficient of friction than conventional steel wear rods. 7

Other objects and advantages of the present invention will become apparent as the description thereof proceeds.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, there is provided a wear rod for a snowmobile ski. The wear rod comprises an elongated base member carrying means for connecting the base member to a ski. The underside of the base member has bonded thereto an elongated polyurethane member with alumina ceramic members embedded therein.

In the illustrative embodiment of the invention, the alumina ceramic members are generally spherical pellets, and the polyurethane member has a generally plastructed in accordance with the principles of the present invention;

ignated with reference numeral 10*comprises an elongated base member 12 which is preferably a cylindrical steel rod having a it inch diameter and a length of benar bottom and planar opposing sides, with the polyurethane having a durometer hardness, exclusive of the embedded members, between on the A scale and 75 on the D scale.

In producing wear rods in accordance with the illustrative embodiment, a plurality of alumina ceramic pellets are introduced into the bottom of an open mold. A polyurethane-forming compound is poured into the mold over the alumina ceramic pellets. The rod is then placed into the mold so that the undersurface of the rod is in the polyurethane-forming compound and the upper surface of the rod is free therefrom. The compound is permitted to set, thereby embedding the alumina ceramic pellets in the compound and bonding the compound to the steel rod.

A more detailed explanation of the invention is provided in the following description and claims and is illustrated in the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary side view of a wear rod contween 2 and 3 feet. The rod is bent in the conventional manner to fit into the conventional recess formed in a snowmobile ski and has connecting means 14 fastened to its upper surface by solder 16 or the like. In the illustrative embodiment, the connecting means 14 comprises a bolt which enters an aperture in the ski and the wear rod is retained against the ski by means of an appropriate nut. It is to be understood, however, that the connecting means 14 could be of various types and numbers and that the specific construction of the connecting means is not significant to the present invention.

The abrasion resistance of the wear rod is greatly increased by bonding to base member 12 an elongated polyurethane member 18 having alumina ceramic members 20 embedded therein. It is preferred that the polyurethane have a durometer hardness, exclusive of the alumina ceramic members, from 50 on the A scale to on the D scale, and that the polyurethane member is formed of a polyether-type polyurethane, although a polyester-type polyurethane could be used. The ceramic members 20 are bodies of bonded alumina (Al O Typically such bodies consist essentially of 99.9 percent alumina by weight, with the remaining constituents being bonding, fluxing and inhibiting agents added in aggregate amounts, as is well-known in the art. Such bodies typically have a hardness on the Knoop K scale of l,7002,000.

A specific example of alumina ceramic members which have been found satisfactory are Metlx alumina ceramic pellets manufactured by the Coors Porcelain Company of Golden, Colorado, and having a diameter of approximately one-sixteenth inch. These pellets are embedded in the polyurethane by introducing them into the bottom of an open mold having a generally fiat bottom and generally planar opposing sides, pouring a liquid polyurethane-forming compound into the mold and placing the undersurface of elongated base member 12 into the liquid polyurethane-forming compound with the upper surface of the elongated base member free therefrom. The polyurethane-forming compound will set to embed the alumina ceramic pellets therein and bond to the undersurface of the elongated base member 12, as shown in FIGS. 1 and 3. It is to be understood that alumina ceramic chips, or other forms different from pellets, could be used.

Substantiallyall of the pellets 20 embedded in the polyurethane will be adjacent the bottom of the member 18, as indicated in FIGS. 1 and 3. It is preferred that the pellet density adjacent the bottom of member 18 be between 30 to 300 per square inch.

It is preferred that the mold have a width that is slightly greater than the width (or diameter) of the elongated base member 12 so that the polyurethane can also be bonded to the sides of the elongated base member 12.

It is seen that when the item is removed from the mold, the polyurethane member 18 will have a generally planar bottom 22 and generally planar opposed sides 26. The rectilinearity has been found desirable for improved stability. In order to increase the adhesion of the bond between the polyurethane and the rod 12, it is preferred that prior to introduction of rod 12 into the mold, the undersurface of rod 12 be roughened. Such toughening could include the provision of knurls, grooves or serrations on the portion of the rod 12 which contacts the polyurethane.

Another method for increasing the adhesion of the bond between the polyurethane and the rod 12 comprises spot welding to the bottom of rod 12 a strip of cold rolled steel that, as a specific example, is A; inch in height and /4 inch wide. When the rod 12 and attached steel strip are introduced into the mold, the polyurethane will fold over the lip formed by the steel strip, thus increasing the adhesion area.

it is preferred that the alumina ceramic members be in the form of pellets having a diameter between one thirty-second inch and one-eighth inch, preferably onesixteenth inch, and that the height of the polyurethane member between the bottom of rod 12 and the bottom '22 of the polyurethane member be between onefourth inch and one-half inch.

An improved wear rod has been described which has greater elasticity than a steel wear rod, provides better stability and increased steering response than the conventional steel rod and has a much higher abrasion resistance than the conventional steel wear rod. Additionally, the provision of a polyurethane member provides a desirable lower coefficient of friction than is provided with steel wear rods. Further, polyurethane has constant properties even at extremely cold temperatures as low as -8() F.

Although an illustrative embodiment of the invention has been shown and described, it is to be understood that various modifications and substitutions may be made by those skilled in the art without departing from the novel spirit and scope of the present invention.

What is claimed is: i

1. A wear rod for snowmobile -skis which.;comprises: an elongated base member; means carried by said base member for connecting said base member to a ski; the underside ofsaid base member having: honded thereto an-elongated polyurethane membenwith alumina ceramicmernbers embedded therein 2. A wear rod for snowmobile skis as described in claim 1, wherein said alumina .ceramic members comprise pellets which are generally spherical in shape.

3. A wear rod for snowmobile skis as described in claim 1, wherein said polyurethane memberis formed of a polyether-type polyurethane.

4. A wear rod for snowmobile skis as described in claim 1, and further including frictional means formed on the underside of the base member for increasing the adhesion of the bond between the polyurethane member and the base member.

5. A wear rod for snowmobile skis as described in claim l, wherein said polyurethane member has a generally planar bottom and planar opposing sides.

6. A wear rod for snowmobile skis as described in claim 1, wherein said polyurethane has a durometer hardness, exclusive of the embedded alumina ceramic members, between 50 on the A scale and on the D scale.

7. A wear rod for snowmobile skis which comprises: an elongated base member carrying means for connecting it to a ski, the underside of said base member having bonded thereto an elongated polyurethane member with alumina ceramic pellets embedded therein; frictional means formed on the underside of the base member for increasing the adhesion of the bond between the polyurethane member and the base member; said polyurethane member having a generally planar bottom and planar opposing sides and having a durometer hardness, exclusive of the embedded ceramic pellets, be-

tween 50 on the A scale and 75 on the D scale. 

2. A wear rod for snowmobile skis as described in claim 1, wherein said alumina ceramic members comprise pellets which are generally spherical in shape.
 3. A wear rod for snowmobile skis as described in claim 1, wherein said polyurethane member is formed of a polyether-type polyurethane.
 4. A wear rod for snowmobile skis as described in claim 1, and further including frictional means formed on the underside of the base member for increasing the adhesion of the bond between the polyurethane member and the base member.
 5. A wear rod for snowmobile skis as described in claim 1, wherein said polyurethane member has a generally planar bottom and planar opposing sides.
 6. A wear rod for snowmobile skis as described in claim 1, wherein said polyurethane has a durometer hardness, exclusive of the embedded alumina ceramic members, between 50 on the A scale and 75 on the D scale.
 7. A wear rod for snowmobile skis which comprises: an elongated base member carrying means for connecting it to a ski, the underside of said base member having bonded thereto an elongated polyurethane member with alumina ceramic pellets embedded therein; frictional means formed on the underside of the base member for increasing the adhesion of the bond between the polyurethane member and the base member; said polyurethane member having a generally planar bottom and planar opposing sides and having a durometer hardness, exclusive of the embedded ceramic pellets, between 50 on the A scale and 75 on the D scale. 